Help: Fn+h lists the keys of the screen you're on, and no screen names its keys any more (#69)

Fn+h on any screen, text fields included, and ? outside Text Entry, open a
panel over the content area: the screen's own keys, then the ones that work
everywhere. Every App declares its keys for the state it is in (pages,
viewers, dialogs and text fields answer for themselves); the App manager
opens the panel and takes every key while it is open.

About 30 hint lines are gone, from every App. What stays on a screen is
state. The first-start Setup keeps its hints and teaches the key; a device
set up before gets one Toast, once. The guide and the FAQ open with it.
`key help` over the consoles.

476 host tests (8 new). Checked on the device with key help and screenshots:
the Launcher, all nine Apps and several of their states. 8.5 KB of flash and
40 bytes of static RAM. Decisions Q196 to Q203 in docs/milestones/U1.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

site/content/faq.md

@@ -6,6 +6,10 @@ template = "guide-page.html"
 toc = true
 +++
 
+## Which keys work on this screen?
+
+Press **<kbd>Fn</kbd> + <kbd>h</kbd>**, on any screen: it lists the keys that work there, then the ones that work everywhere. <kbd>?</kbd> does the same when you are not typing text. The screens themselves never name their keys, so this is the one key to remember. See [The basics](/guide/basics/).
+
 ## Can I send messages over the mesh?
 
 **Not yet.** The LoRa Scanner **listens** to Meshtastic traffic and shows what it hears, but nothing is transmitted. A mesh messenger is the goal and is planned in two milestones, one for receiving and one for transmitting; it waits for a second node to test against.